The present invention relates to a female connector half of an electrical connector (hereinafter referred to as "female connector") that permits the passage of low signal current in such applications as electric wire harnesses in automobiles, characterized in that said female connector is formed in a monolithic structure with a novel copper-base alloy.
A female connector generally consists, as shown in FIG. 2, of a socket portion 1 and a wire-connecting portion 2, said socket portion having therein a spring element 3 and accepting the insertion of a male connector.
While electrical connectors that permit the passage of low signal currents in such applications as electric wire harnesses in automobiles are required to have several properties, female connector halves must particularly meet the following requirements: good spring properties and amenability to working or machining into complex shapes; ease of selective plating with gold intended to reduce the contact resistance of the contact area; and ease of tin plating performed to prevent discoloration of substrate surfaces and to provide good solderability.
However, no single materials available today possess all of these properties simultaneously, and female connectors are conventionally fabricated from combinations of spring materials having good spring properties with frame materials featuring high ratings of machinability. Namely, the spring element 3 shown in FIG. 2, and the frame element (the socket portion 1 and the wire-connecting portion 2 shown in the same figure are prepared in two separate steps and they are assembled later into a single element. Commonly employed spring materials are beryllium copper (C-1720) and Cu-9% Ni-6% Sn alloy, and typical frame materials are made of brass (C-2600) or Cu-0.1% Fe-0.03% P alloy that feature high ratings of machinability.
This prior art technique, however, has had the following problems.
(1) Spring materials are gold plated in the contact area in order to reduce contact resistance, and tin plated in other areas in consideration of corrosion resistance and solderability. However, materials used as spring elements exhibit the intended spring properties only after they are age-hardened in the temperature range of 315.degree.-450.degree. C. following pressing into a desired shape. This requires plating with a desired metal after pressing but this post-pressing plating method leads to an increased production cost as compared with a method in which plating precedes the pressing operation.
(2) Beryllium copper is easily workable when it is in a unhardened state but its high price makes it an uneconomical material for use in the fabrication of a monolithic female connector half.
(3) Making spring and frame members from different alloys and assembling them into a single element are not cost-effective because of the increased number of fabrication steps involved.
(4) With the recent tendency of using electrical connectors in more hostile environments, it has become necessary to ensure that the contact pressure will not change under prolonged exposure to temperatures between about 150.degree. and 200.degree. C. However, the prior art connectors fabricated from the combination of two different materials are unable to meet this requirement.
(5) The scrap of the prior art two-piece female connector cannot be recycled by an economical method since separating the spring material from the frame material requires costly treatments.